That would be very rare however sometimes lung cancer may appear as pneumonia discuss the situation with the doctors.

It's the lung cancer that can cause pneumonia by blocking the airways.

No, generally, people do develop pneumonia when part of The lung gets blocked off by a tumor. I do not think there is any evidence that pneumonia can cause lung cancer.

Pneumonia and lung cancer are distinct entities. Lung cancer can predispose a patient to getting pneumonia as a result of the tumor blocking the airways, as is seen in post-obstructive pneumonia. However, the reverse is not true.

Very unlikely for pneumonia to progress to lung cancer. Most likely there was lung cancer with associated pneumonia.

No, the cancer caused the pneumonia.

No. Most likely, she has already had cancer which obstructed the bronchus and obstructive pneumonia.

Not usually. The cause of her lung cancer is the smoking she has been doing all those years.

Short answer: Not with only one episode of pneumonia.
Longer answer: We know that chronic irritation of the lung can lead to a type of lung cancer called Squamous Cell, but by chronic, I mean years and years of nonstop irritation. And even then it would have to be in the same location as the irritation. IF the cancer was in the same spot as the pneumonia, the likely answer is that the cancer was there at the time, it just could not be seen because of the pneumonia.

No, is the short answer. There could have been a small tumor in the lung which perhaps blocked off the airway passage and caused pneumonia down the track. If the tumor is small, it cannot be visualized on imaging studies. It was probably picked up as it got larger over time.

No pneumonia cannot cause lung cancer.